Excitation of Molecular Vibration on Collision

We have calculated the cross section for excitation of the first vibrational level in the collision of two hydrogen molecules in the ground state. A partial wave analysis is used, and the radical equation is solved for many values of angular momentum using the high speed computer Univac. We find that the major contribution to the total cross section comes from large values of the angular momentum, of the order of 10 to 20, and that values of the angular momentum up to about 80 must be considered. In the energy range of interest, 0.5 to 2 ev, the total cross section is obtained, and the vibrational relaxation time is also computed. The value of the cross section is found by calculation to be very sensitive to the precise values of the intermolecular potential used.